While the present invention is generally applicable to sequentially distribute fluids from a source which is at least at a modest pressure above ambient over a number of outputs, a principle aim of the invention is for irrigation systems comprised of irrigation lines or circuits intended to feed water to a series of sprinkler heads, drip irrigation outlets and the like. It is generally the case that the available water source pressure limits the total number of irrigation devices which may be supplied by any one circuit. If this limit is exceeded, the devices fed by the circuit generally receive too little water, or water at too low a pressure to properly perform their function. Consequently, it is desirable to lay out irrigation systems comprised of a number of different circuits.
Another rising concern in the design of such systems relates to the prudent management of water. Being able to group the plant materials to be watered according to their water quantity requirements in separate circuits permits far more flexible and economical use of water, by appropriately adjusting the time periods for which the different circuits are supplied with water.
The above advantage or indeed the need of using multiple circuits has been recognized previously. There are available a variety of systems for switching a source of water sequentially between a number of circuits. However, such devices are generally electrically operated valve systems, which are expensive and relatively complicated, usually required to be installed by professionals. Also, owing to the more complicated nature of such systems, their operation, adjustment and maintenance represent more formidable problems.